linux-kernel - Re: [PATCH v5 1/4]: perf/core: use rb trees for pinned/flexible groups

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Message-ID: <877ez6vtos.fsf@ashishki-desk.ger.corp.intel.com>
Date:   Tue, 18 Jul 2017 15:02:59 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Andi Kleen <ak@...ux.intel.com>, Kan Liang <kan.liang@...el.com>,
        Dmitri Prokhorov <Dmitry.Prohorov@...el.com>,
        Valery Cherepennikov <valery.cherepennikov@...el.com>,
        Mark Rutland <mark.rutland@....com>,
        David Carrillo-Cisneros <davidcc@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 1/4]: perf/core: use rb trees for pinned/flexible groups

Alexey Budankov <alexey.budankov@...ux.intel.com> writes:

> +static void
> +perf_event_groups_rotate(struct perf_event_groups *groups, int cpu)
> +{
> +	struct rb_node *node;
> +	struct perf_event *node_event;
> +
> +	WARN_ON_ONCE(!groups);

This seems redundant.

> +
> +	list_rotate_left(&groups->list);
> +
> +	/* will replace rotation above in patch v5 3/4
> +
> +	node = groups->tree.rb_node;
> +
> +	while (node) {
> +		node_event = container_of(node,
> +				struct perf_event, group_node);
> +
> +		if (cpu < node_event->cpu) {
> +			node = node->rb_left;
> +		} else if (cpu > node_event->cpu) {
> +			node = node->rb_right;
> +		} else {
> +			list_rotate_left(&node_event->group_list);
> +			break;
> +		}
> +	}
> +
> +	*/

Please don't do this, it doesn't add clarity.

> +static int
> +perf_event_groups_iterate(struct perf_event_groups *groups,
> +		perf_event_groups_iterate_f callback, void *data)
> +{
> +	int ret = 0;
> +	struct perf_event *event;
> +
> +	WARN_ON_ONCE(!groups);
> +
> +	list_for_each_entry(event, &groups->list, group_list_entry) {
> +		ret = callback(event, data);
> +		if (ret)
> +			break;
> +	}
> +
> +	/* will replace itration above in patch v5 4/4
> +
> +	for (node = rb_first(groups); node; node = rb_next(node)) {
> +		node_event = container_of(node,	struct perf_event, group_node);
> +		list_for_each_entry(event, &node_event->group_list,
> +				group_list_entry) {
> +			WARN_ON_ONCE(!(event->cpu == node_event->cpu));
> +			ret = callback(event, data);
> +			if (ret) {
> +				return ret;
> +			}
> +		}
> +	}
> +
> +	*/

Ditto.

Regards,
--
Alex